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| United States Patent |
5,200,430
|
|
Federman
|
April 6, 1993
|
Debridement of bodily cavities using debridement fluids
Abstract
Foreign substances may be removed from a mammalian body cavity containing
an aqueous phase by injecting into the cavity a water-immiscible,
optically clear, biocompatible debridement fluid to at least partially
displace the aqueous phase, and removing the aqueous phase and the foreign
substances. In addition, a method is provided for visualizing a
transparent foreign substance in a mammalian body cavity using a
water-immiscible, optically clear, biocompatible fluid having a refractive
index different from that of water. The debridement fluid may also be used
to reposition desirable substances, such as a lens in an ocular cavity, or
to remove a secondary membrane from a cavity lining or structure.
Preferably, a liquid heavier than water, such as a perfluorocarbon liquid,
is used as the debridement fluid.
| Inventors:
|
Federman; Jay L. (Philadelphia, PA)
|
| Assignee:
|
Escalon Ophthalmics, Inc. (Skillman, NJ)
|
| Appl. No.:
|
672972 |
| Filed:
|
March 21, 1991 |
| Current U.S. Class: |
514/772; 424/9.1; 604/500; 604/521 |
| Intern'l Class: |
A61K 047/00 |
| Field of Search: |
424/5
514/772
|
References Cited
U.S. Patent Documents
| 4490351 | Dec., 1984 | Clark, Jr. | 424/5.
|
Other References
Nabih, M., et al., "Experimental Evaluation of Perfluorophenanthrene as a
High Specific Gravity Vitreous Substitute: A Preliminary Report,"
Ophthalmic Surgery, 20(4):286-93 (1989).
Chang, S., et al., "Experimental Vitreous Replacement With
Perfluorotributylamine," Am. J. Ophth., 103:29-37 (1987).
|
Primary Examiner: Waddell; Frederick E.
Assistant Examiner: Fay; Zohreh A.
Attorney, Agent or Firm: Panitch Schwarze Jacobs & Nadel
Claims
I claim:
1. A method for removing foreign substances from a mammalian body cavity
containing an aqueous phase comprising injecting into the cavity at a
location near the lower portion of the cavity a water-immiscible,
optically clear, biocompatible debridement fluid having a specific gravity
greater than water in an amount sufficient to at least partially displace
the aqueous phase, removing the aqueous phase and the foreign substances
from the cavity at a location near the upper portion of the cavity and
removing the debridement fluid.
2. The method according to claim 1, wherein the debridement fluid is
injected in an amount sufficient to displace all of the aqueous phase.
3. The method according to claim 1, wherein the debridement fluid comprises
perfluorocarbon liquid.
4. The method according to claim 3, wherein the perfluorocarbon liquid is
selected from the group consisting of perfluoropentane,
perfluorodimethylcyclobutane, perfluoromethylcyclopentane,
perfluorohexane, perfluoromethylcyclohexane, perfluoroheptane,
perfluorooctane, perfluoro-1,3-dimethylcyclohexane, perfluorodecalin,
perfluoro-1-methyldecalin, perfluorotributylamine,
perfluorododecahydrofluorene and perfluorotetra-decahydrophenanthrene.
5. The method according to claim 4, wherein the perfluorocarbon comprises
perfluorooctane or perfluorodecalin.
6. The method according to claim 1, wherein the bodily cavity is the
abdominal cavity, thoracic cavity, fallopian tube, uterine cavity,
intraocular cavity, intra-articular cavity, central nervous system
ventricular cavity or dural spaces.
7. The method according to claim 1, wherein the foreign substances comprise
foreign cells, inflammatory cells, blood cells, tumor cells, tissue
debris, sera, protein, bacteria, virus, fungi, vitreous, silicone oil or
foreign bodies.
8. The method according to claim 3, further comprising perfusing the liquid
perfluorocarbon with oxygen prior to injection into the cavity.
9. The method according to claim 8, further comprising repeatedly perfusing
the perfluorocarbon liquid after injection into the cavity to maintain a
predetermined oxygen concentration level.
10. A method for visualizing a transparent foreign substance or aqueous
phase in a mammalian body cavity comprising injecting into the cavity a
water-immiscible, optically clear, biocompatible fluid having a refractive
index sufficiently different from the refractive index of the foreign
substance or aqueous phase to cause visible refraction at the interface
between the foreign substance or aqueous phase and the biocompatible fluid
in an amount sufficient to at least partially surround the foreign
substance, introducing visible light into the cavity and visualizing the
foreign substance as an outline formed at the interface between the fluid
and the transparent foreign substance or aqueous phase.
11. The method according to claim 10, wherein the fluid comprises
perfluorocarbon liquid.
12. The method according to claim 11, wherein the perfluorocarbon liquid is
selected from the group consisting of perfluoropentane,
perfluorodimethylcyclobutane, perfluoromethylcyclopentane,
perfluorohexane, perfluoromethylcyclohexane, perfluoroheptane,
perfluorooctane, perfluoro-1,3-dimethylcyclohexane, perfluorodecalin,
perfluoro-1-methyldecalin, perfluorotributylamine,
perfluorododecahydrofluorene and perfluorotetradecahydrophenanthrene.
13. The method according to claim 10, wherein the biocompatible fluid has a
refractive index at least 0.01more or less than water.
14. The method according to claim 10, wherein the body cavity is the
abdominal cavity, thoracic cavity, fallopian tube, uterine cavity,
intraocular cavity, intra-articular cavity, central nervous system
ventricular cavity or dural spaces.
15. A method for removing foreign substances from tissue within a mammalian
body cavity where the foreign substances form a layer which overlies the
tissue, comprising injecting into the cavity a water-immiscible,
biocompatible fluid, having a specific gravity greater than water and the
tissue, in an amount sufficient to cover the tissue, and mechanically
pulling the foreign substances away from the tissue.
16. The method according to claim 15, wherein the fluid comprises
perfluorocarbon liquid.
17. The method according to claim 16, wherein the perfluorocarbon liquid is
selected from the group consisting of perfluoropentane,
perfluorodimethylcyclobutane, perfluoromethylcyclopentane,
perfluorohexane, perfluoromethylcyclohexane, perfluoroheptane,
perfluorooctane, perfluoro-1,3-dimethylcyclohexane, perfluorodecalin,
perfluoro-1-methyldecalin, perfluorotributylamine,
perfluorododecahydrofluorene and perfluorotetra-decahydrophenanthrene.
18. The method according to claim 15, wherein the tissue comprises the
retina.
19. The method according to claim 15, wherein the foreign substances
comprise a secondary membrane.
Description
FIELD OF THE INVENTION
The present invention relates to methods for the debridement of enclosed
body cavity spaces which must remain substantially free of foreign
substances to function properly. More particularly, the invention is
directed to removal of foreign substances from the eye.
BACKGROUND OF THE INVENTION
Within the mammalian body are many cavities. These include organ cavities
and tissue cavities within which one or more organs are located. Depending
on the particular cavity, these cavities are lined by endothelial cells,
epithelial cells and/or basilamina material, which is produced by cellular
foot plate secretions. Such tissue and organ cavities include the
abdominal cavity, thoracic cavity, fallopian tube, uterine cavity,
intraocular cavity, joint space or intra-articular cavity, central nervous
system ventricular cavity and the dural spaces. Despite different
functions, all cavities share the common requirement that they must be
kept clean of foreign substances to maintain normal function.
As used in this disclosure, the term "foreign substances" is not limited to
debris and fluid from outside the body but will be recognized in its
broadest sense by those skilled in the medical arts to include foreign
cells, which include mal- or dysfunctioning or displaced indigenous cells,
proteins, sera, inflammatory cells, blood cells, tumor cells, tissue
debris, infectious organisms (i.e., bacteria, virus and fungi) in addition
to foreign bodies, such as glass, metal and wood, as well as other solid
and liquid substances not normally found or desirable in a properly
functioning body cavity. Under normal conditions, these cavities are
essentially selfcleaning, being constantly cleaned by a system of
scavenger cells and macrophages and constant flushing by freshly
manufactured aqueous fluids.
The presence of foreign substances in tissue or organ cavities due to
invasion, infection, deterioration, age or break down of the self-cleaning
system can have symptomatic and pathological ramifications. For example,
in the eye, the presence of foreign substances can produce clouding in the
intraocular cavity, causing blurred or cloudy vision. In addition, the
presence of foreign substances in large enough quantities can cause
scarring, production of fibrous tissue membrane and mass, tumors and
infection. In the joint, the presence of foreign substances can result in
increased friction, inflammation and pain. Generally, the end result is
mal- or dysfunction of the tissue or organ cavity.
The visual process and smooth movement of the joints, in particular, each
requires a clean, clear environment, free of anatomic distortions
secondary to inflammatory fibrous scar tissue formation, dislocated
tissues and foreign bodies. Many surgical and medical procedures are
presently available to prevent or alleviate cavity dysfunction due to
foreign substance build-up by anatomically reconstructing and cleaning
cavity spaces after they have been destroyed or are in a state of
dysfunction as a result of some pathologic event. However, surgery itself
has pathological consequences. Surgical procedures, including those that
minimize cavity invasion using fiber optics and microsurgical tools,
inevitably involve cutting and manipulating, resulting in the release of
tissue, sera and cellular debris. Accordingly, a primary goal in the
surgical management of any tissue or organ cavity is the meticulous
cleansing of the cavity space of foreign substances to effect and ensure
speedy recovery and prompt return of a normal functioning cavity
In conventional surgical procedures, even delicate microsurgical
procedures, it is virtually impossible to identify and remove all foreign
substances from the cavity and cavity surfaces. Moreover, the more
involved and complicated the surgical procedures, the greater the amounts
of residual tissue, sera and cellular debris created within the cavity
space and on tissue surfaces Without effective removal, healing time will
be longer and complete recovery will be more difficult.
Conventional debridement or cleansing of body cavities during and following
surgery comprises flushing the cavity with biological fluids, such as
sterile saline solutions, and mechanical removal. Such debridement does
not completely remove all foreign substances and is highly ineffective in
removing water soluble and very small foreign substances.
In view of the deficiencies of the prior art, it would be desirable to have
a method for the debridement of mammalian bodily cavities which is safe,
relatively simple and highly effective in removing foreign substances.
BRIEF SUMMARY OF THE INVENTION
According to the present invention, a method for removing foreign
substances from a mammalian cavity containing an aqueous phase comprises
injecting into the cavity a water-immiscible, optically clear,
biocompatible debridement fluid in an amount sufficient to replace or at
least partially displace the aqueous phase, and removing the aqueous phase
and the foreign substances from the cavity, or repositioning desirably
retained materials (such as an intraocular lens in the ocular cavity), by
pushing with the surface of the fluid.
In addition, the present invention is directed to a method for visualizing
a transparent foreign substance in a mammalian body cavity comprising
injecting into the cavity a water-immiscible, optically clear,
biocompatible fluid having a refractive index sufficiently different from
that of the foreign substance to cause visible refraction at the interface
between the foreign substance and the biocompatible fluid, the fluid being
injected in an amount sufficient to at least partially surround the
foreign substance, introducing visible light into the cavity, and
visualizing the foreign substance as an outline formed at the interface
between the fluid and the transparent foreign substance.
Further according to the present invention, a method is provided for
removing foreign substances from tissue within a mammalian body cavity
wherein the foreign substances form a layer positioned in overlying
relation to the tissue, comprising injecting into the cavity a
water-immiscible, biocompatible fluid having a specific gravity greater
than water and the tissue, the fluid being injected in an amount
sufficient to cover the tissue, and mechanically pulling the foreign
substances away from the tissue.
The methods of the present invention are preferably performed using
perfluorocarbon liquids as the water-immiscible, biocompatible fluids.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing summary of the invention, as well as the following detailed
description of preferred embodiments, will be better understood when read
in conjunction with the appended drawings. For the purpose of illustrating
the invention, there are shown in the drawings embodiments which are
presently preferred, it being understood, however, that the invention is
not limited to the specific arrangements and instrumentalities disclosed.
In the drawings:
FIG. 1 is a generalized, schematic cross-sectional view of a human eye
identifying the major components thereof;
FIG. 2a is a generalized, schematic cross-sectional view of a human eye
illustrating a first embodiment of the method of the present invention;
FIG. 2b is a generalized, schematic cross-sectional view of a human eye
illustrating a later stage of the embodiment illustrated in FIG. 2a;
FIG. 3a is a generalized, schematic cross-sectional view of a human eye
illustrating a second embodiment of the present invention;
FIG. 3b is a generalized, schematic cross-sectional view of a human eye
illustrating a later stage of the embodiment illustrated in FIG. 3a;
FIG. 4a is a generalized, schematic cross-sectional view of a human eye
having sub-retinal debris;
FIG. 4b is a generalized, schematic cross-sectional view of a human eye
illustrating a third embodiment of the present invention for removing
subretinal debris as shown in FIG. 4a;
FIG. 5 is a generalized, schematic cross-sectional view of a human eye
illustrating a fourth embodiment of the present invention; and
FIG. 6 is a generalized, schematic cross-sectional view of a human eye
illustrating a fifth embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawings, wherein the numerals indicate like elements
throughout, there are shown in FIGS. 2 through 6 preferred applications of
the present invention. Although the methods of the present invention apply
to the debridement of body cavities generally, methods are described and
exemplified below with specific reference to the debridement of the
intraocular cavity. It will be readily appreciated and understood by one
skilled in the medical arts in view of this disclosure, however, how the
methods exemplified below may be adapted for use in the debridement of
other body cavities, as well as in other types of debridement of the
intraocular cavity.
According to the present invention, methods for the debridement of cavities
in the mammalian body comprise the intraoperative use of a biocompatible
debridement fluid. While not wishing to be bound by any particular theory,
the inventor notes that most undesirable foreign substances in body
cavities are generally miscible in water or show an affinity for aqueous
fluids. Accordingly, the debridement fluid should be water-immiscible so
that the foreign substance-containing water phase is distinct from and is
displaced by the water-immiscible debridement fluid.
Preferably, the water-immiscible fluid is optically clear, although the
liquid could have a color or have a color added using appropriate dyes as
desired. The fluid should be optically clear so that the surgeon may
visualize the foreign substances desired to be removed from the bodily
cavity and may observe the debridement process itself. In addition, it is
preferred that the debridement fluid have a low viscosity for ease of
insertion and removal of the fluid into and from the body cavity. It is
also presently preferred that the debridement fluid be heavier than water
so that the foreign substance-containing aqueous phase can be floated out
of a closed cavity. This is particularly preferred in those surgical
procedures where the position of the patient places the particular body
cavity in a position where the bottom (lowermost point) of the cavity is
relatively inaccessible to surgical apparatus. The eye of a human patient
in a supine position is one example. In cavities where it may be desired
to drain foreign substance-containing aqueous phase from the lower or
bottom end of the cavity, a debridement fluid lighter than water may be
desired.
The presently preferred debridement fluid comprises perfluorocarbon liquids
(also called liquid perfluorocarbons). Accordingly, the remainder of this
description will be in terms of perfluorocarbon liquids as the debridement
fluid. It will be understood, however, that the methods described may be
carried out with other debridement fluids having the desired properties
discussed above, such as silicone fluids which, although lighter than
water, are water-immiscible, optically clear, have low viscosities and are
biocompatible.
Many perfluorocarbon liquids are known and described in, for example, U.S.
Pat. No. 4,490,351 of Clark, Jr. Perfluorocarbon liquids are generally
biocompatible and have been used widely as blood substitutes because of
the ability to dissolve substantially more oxygen and carbon dioxide
therein than water or other aqueous phases. It is presently believed that
virtually any perfluorocarbon liquid may be used to debride bodily
cavities in accordance with the present invention. Table 1 contains the
physical and chemical characteristics of thirteen perfluorocarbon liquids
which are suitable for use in accordance with some or all of the
embodiments of the present invention. The physical and chemical
characteristics of water are also included in Table 1 for comparison. The
thirteen samples, in order with reference to Table 1, include:
1. Perfluoropentane (C.sub.5 F.sub.12),
2. Perfluorodimethylcyclobutane (C.sub.6 F.sub.12),
3. Perfluoromethylcyclopentane (C.sub.6 F.sub.12),
4. Perfluorohexane (C.sub.6 F.sub.14),
5. Perfluoromethylcyclohexane (C.sub.7 F.sub.14),
6. Perfluoroheptane (C.sub.7 F.sub.16),
7. Perfluorooctane (C.sub.8 F.sub.18),
8. Perfluoro-1,3-dimethylcycloh (C.sub.8 F.sub.16),
9. Perfluorodecalin (C.sub.10 F.sub.18),
10. Perfluoro-1-methyldecalin (C.sub.11 F.sub.20),
11. Perfluorotributylamine ((C.sub.4 F.sub.9).sub.3 N),
12. Perfluorododecahydrofluorene (C.sub.13 F.sub.22) and
13. Perfluorotetra-decahydrophenanthrene (C.sub.14 F.sub.24).
The presently preferred perfluorocarbon liquids are perfluorooctane,
perfluorodecalin and perfluorotetradecahydrophenanthrene, with the first
two of these being most preferred.
TABLE 1
__________________________________________________________________________
PHYSICAL AND CHEMICAL CHARACTERISTICS OF PERFLUOROCARBON FLUIDS AT
25.degree. C. (UNLESS OTHER TEMPERATURE STATED)
1 2 3 4 5 6 7 8 9 10 11 12 13 WATER
__________________________________________________________________________
Boiling
29 45 48 57 76 80 101 102 142 155 174 194 215 100
point, .degree.C.
Distillation
28-32 50-60
73-78
75-90
99-107
92-104
135- 165-
range (90% 143 185
min.
distilled),
.degree.C.
Freezing
-120
-32 -70 -90 -30 -95 -65 -70 -8 -70 -50 -40 -20 0
point, .degree.C.
Molecular
288 300 300 338 350 388 438 400 462 512 671 574 624 18
weight
Specific
1.604
1.6718
1.682
1.682
1.788
1.73
1.77
1.828
1.917
1.972
1.88
1.984
2.03
1
gravity
Kinematic
0.29
0.59
0.615
0.39
0.87
0.55
0.8 1.06
2.66
3.25
2.8 4.84
14 0.9
viscosity,
cSt
Surface
9.4 11.6
12.6
12 15.4
13 14 16.6
17.6
18.5
16 19.7
19 72
tension,
mN/m
Re- 1.2383
1.2555
1.265
1.2509
1.2781
1.261
1.271
1.2895
1.313
1.3195
1.291
1.3289
1.3348
1.333
fractive
index
Vapour
862 505 368 300 141 105 39 48 8.8 2.9 1.7 <1 <1 31.6
pressure,
mbar
Heat of
90.8
84.9
90.5
86.7
85.9
79.4
92 82.9
78.7
75.5
71.1
71 68 2257
vaporiza-
tion at
boiling
point,
kJ/kg
Specific
1.05
1.13
0.878
1.07
0.963
1.045
1.045
0.963
1.05
1.09
1.045
0.92
1.07
4.18
heat,
kJ/kg .degree.C.
Thermal
64 66.4
60 59.9
60 64 60.4
57 57.5
66 56 52.6
586
con-
ductivity,
mW/m .degree.C.
Critical
148.7
171.7
180.8
178 212.8
205 229 241.5
292 313.4
294 357.2
377 374
tempera-
ture,
.degree.C.
Critical
20.48
21.5
22.64
18.34
20.19
17.5
16.6
18.81
17.53
16.6
11.4
16.2
14.6
221
pressure,
bar
Critical
1.626 1.567
1.582
1.522 1.52
1.521
1.5 1.59
1.58
volume,
l/kg
Co- 0.00189 0.00167
0.00159
0.00138
0.0015
0.0014
0.00123
0.00104
0.00097
0.0012
0.00078
0.00075
0.0002
efficient
of ex-
pansion
ml/ml .degree.C.
Acoustic
468 515 578 542 575 609 711 655 875 1498
velocity,
m/s
__________________________________________________________________________
Those skilled in the art will appreciate, however, in view of the present
disclosure that other perfluorocarbon liquids having the desired
properties described herein may be used as debridement fluids in
accordance with the present invention.
Where the debridement fluid is intended for use in the intraocular or other
cavity where it is important that the surgeon visualize the foreign
substance or observe the debridement process (discussed below), it is
preferred that the perfluorocarbon liquid have a refractive index which
differs from the refractive index of the cavity aqueous phase by an amount
or degree sufficient to allow visualization of the interface between the
aqueous phase and the debridement fluid. As an analogous example, oil is
immiscible with water and has a different refractive index. When oil is
added to the surface of a water container, the oil does not mix with the
water and can be seen to be floating on the top of the water surface. Even
when shaken, an emulsion results and individual oil droplets can be
visualized by the dark border at the interface of the oil and water due to
visible refraction caused by the different refractive indices of the two
liquids.
In accordance with the present invention, debridement fluids may be used to
clean cavity spaces intraoperatively and, in particular, in conjunction
with closed cavity surgery, such as operations on the eye and arthroscopic
procedures. One skilled in the art will appreciate in view of this
disclosure that many procedures to surgically remove foreign substances
from body cavities may be performed using the debridement fluids of the
present invention. Further, many known surgical procedures, such as the
vitrectomy discussed below, may be supplemented with the use of such
debridement fluids to avoid complications resulting from the presence of
foreign substances in body cavities after surgery.
For example, debridement in accordance with the present invention may be
performed in the intraocular cavity, which during surgery is sealed with
the exception of two or three small incisions for surgical apparatus.
Vitroretinal surgery, for example, is a widely known procedure used for
various eye disorders. One specific vitroretinal procedure is pars plana
vitrectomy or the surgical removal of the vitreous of the eye. Referring
to FIG. 1, the vitreous is an aqueous phase transparent collagen
fiber/hyaluronic acid gel matrix which fills the intraocular or vitreous
space cavity 20 of the eye 10. The vitreous is normally optically clear,
allowing light passing through the lens 25 to reach the retina 30 without
distortion. When the vitreous breaks down or liquefies, removal is
sometimes indicated.
During pars plana vitrectomy, as many as three incisions are made in the
pars plana in three different quadrants, usually at 10 o'clock, 2 o'clock
and in the infratemporal quadrant (relative to the eye positioned in a
supine patient). This is schematically illustrated in FIGS. 2a, 2b, 3a,
3b, 4b, 5 and 6, generally. An infusion cannula (not shown) is sewn into
the infratemporal incision to keep the eye constantly filled with the
aqueous phase liquid usually used for this surgery (e.g., a modified
balanced salt solution). The superior incisions are generally used for
working instruments, such as fiber optic lights (not shown), blunt-tipped
needles for injection (insertion apparatus 100) or aspiration (removal
apparatus 120), forceps, scissors and mechanical cutters (not shown).
Visualization of the procedure is done through the pupil with an operation
microscope. Once removed surgically, small pieces of the vitreous remain
as well as serum and cellular debris generated from surgical trauma.
Referring to FIG. 2a, in accordance with the present invention, debridement
fluid 200 is introduced into the intraocular cavity of the eye 10 through
an incision preferably in the superior region 32 (see FIG. 1) between the
front edges 34 of the retina 30 and the ciliary muscles 36 or at a point
where insertion apparatus 100, such as a needle-like instrument, may be
inserted so that its opening 110 is near a dependent spot in the
intraocular cavity, typically just over the retina at the back or lowest
point (as shown in the drawings) of the eye (when the patient is lying
supine).
The vitreous and any surrounding aqueous phase 210, which are lighter than
the debridement fluid (here perfluorocarbon liquid), essentially float on
the perfluorocarbon liquid debridement fluid 200. This phenomenon allows
the emulsified or liquefied vitreous and the aqueous phase to be
conveniently withdrawn from the cavity at a point near the front of the
cavity (the top relative to the patient's position) by passive egress
through the second superior incision or using suction or removal apparatus
120, such as a foot-activated variable suction pump attached to a
blunt-tipped needle.
As the level of the debridement fluid 200 rises in the cavity, the removal
apparatus 120 may be repositioned as illustrated, for example, in FIG. 2b
for removal of all of the aqueous phase 210 and entrained foreign
substances 220. In an aphakic patient (lens removed), the removal
apparatus could even extend through the space between the ciliary muscles
36 and zonular fibers 27 where the lens 25 was, through the pupil of the
iris 50, and into the anterior chamber 55 to remove aqueous phase and
entrained foreign substances from that area of the ocular cavity as well.
Simultaneous injection and removal maintains desired cavity pressure and
allows for a controlled, measured removal of the aqueous phase and foreign
substances.
Debridement fluid is injected into the eye in a preferably slow,
controlled, continuous manner to avoid creating an emulsion or
fish-egging. An emulsion is generally not desired because complete
displacement of the aqueous phase is more difficult to obtain and observe.
Especially in pressure sensitive cavities, such as the eye, care should be
taken to avoid increasing cavity pressure to a point dangerous to the
integrity of cavity tissues or to a point where arterial occlusion may
occur.
Debris and other foreign substances may be removed from a body cavity where
debridement fluid is injected into the cavity in an amount sufficient to
replace or displace and dislodge the aqueous phase foreign substances from
the cavity. Where it is desired to rid the cavity of all, randomly located
foreign substances, for example, this may require enough debridement fluid
to fill the cavity interior. On the other hand, it is not always necessary
to completely fill the cavity with debridement fluid. Thus, debridement
fluid could partially fill the cavity, and the aqueous phase could be
aspirated off the top of the perfluorocarbon liquid (or other heavier than
water fluid) on which the aqueous phase is floating. Air or other gas
could fill the remainder of the cavity. One skilled in the medical arts
will recognize the amount of debridement fluid necessary to remove
unwanted aqueous phase and foreign substances in a given debridement
procedure in view of this disclosure.
With the cavity completely or partially filled with debridement fluid, the
aqueous phase and foreign substances are displaced and removed from the
cavity. Any aqueous phase or foreign substances remaining may, where
desired, be visualized (discussed below) for mechanical intervention or
additional debridement with fresh debridement fluid.
Certain surgical procedures in the eye to repair retinal detachment are
performed by filling the intraocular cavity with silicone fluid. In some
cases, it becomes necessary to remove the silicone. Silicone fluid is
lighter than and immiscible with water and is also immiscible with
perfluorocarbon liquids. Accordingly, it is also possible using the
methods of the present invention to displace silicone fluid by infusing
the intraocular cavity with perfluorocarbon liquid to displace silicone
fluid in a manner similar to removal of the liquefied vitreous and aqueous
phase discussed above.
The specific gravity of the debridement fluid of the present invention can
also facilitate repositioning or removal of certain ocular bodies. For
example, as illustrated in FIGS. 3a and 3b, because intraocular lenses are
formed of materials, such as polymethylmathacrylic (PMMA), which float in
perfluorocarbon liquids, the infusion of perfluorocarbon liquid into the
ocular cavity can be used to float the intraocular lens back into the
correct position for suturing or out of the eye in a manner similar to the
method for removing other foreign substances discussed generally above.
Perfluorocarbon liquid debridement fluid 200 injected into the eye cavity
floats an intraocular lens 300 as well as the aqueous phase 210. Using
well known surgical tools, the lens 300 is appropriately positioned during
perfluorocarbon infusion. As seen in FIG. 3b, when the perfluorocarbon
liquid level approaches the desired level, near the iris 50, the
intraocular lens 300 may be sutured into position. Alternatively, the lens
may be removed via an incision in the eye (not shown) as desired.
In another embodiment, the debridement fluid may be used in accordance with
the present invention to assist in the removal of subretinal pathologic
formations, such as hemorrhages, disciform scars, cysts, parasites,
larvae, worms, mobile tumors, dislocated cataracts or intraocular lenses
and aqueous fluids collected under areas where the retina 30 becomes
detached from the choroid 40. As illustrated in FIGS. 4a and 4b, to remove
a foreign substance 230 (whether liquid, solid, gas or a combination of
these) from behind the retina 30 in accordance with the present invention,
perfluorocarbon liquid debridement fluid 200 is injected into the
intraocular cavity, preferably near the back (bottom) of the retina and
proximate the unwanted foreign substance 230, to displace the debris.
Where necessary or desired, a retinal incision 45 may facilitate removal
of the foreign substance from behind the retina 30. Normally, however, by
means of gravity, the relatively denser perfluorocarbon liquid injected
into the intraocular cavity tends to compress the retina, gradually
working the foreign substance 230 including any aqueous phase toward the
edge 34 of retina 30 as the liquid fills the cavity, thereby facilitating
release of any aqueous phase and foreign substance from the subretinal
space, and hydraulically urging the retinal layer to return to its proper
position for reattachment.
To ensure the complete and effective removal of the aqueous phase,
including cellular and fluid debris, in particular small and even
microscopic particulate debris and other foreign substances dissolved in
the aqueous phase, it may be desired according to another embodiment of
the invention to visualize the debridement process. Visualization using
debridement fluid in accordance with the present invention may also help
facilitate identification and removal of difficult to see foreign
substances. Opaque foreign substances present no visualization problems.
However, vitreous fragments and other transparent materials may also be
identified by infusing the cavity with debridement fluid. Visualization
may also be desired to identify and reposition or remove displaced or
dislocated intraocular lenses, dislocated cataracts or dislocated nuclear
and/or cortical cataract material (a complication generated by
phacoemulsification) and other foreign or ocular substances in the
posterior cavity of the eye.
Accordingly, referring to FIG. 5, in this embodiment, it is presently
preferred to use a debridement fluid 200 which has a refractive index
sufficiently different from the refractive index of water to cause visible
refraction at the interface or boundary between aqueous phase and/or
foreign substance on the one hand and lo the debridement fluid on the
other hand. Use of such debridement fluid creates, when subjected to
light, a visible boundary (black line or plane) or outline 250 at the
interface between the debridement fluid 200 and any aqueous phase or
debris 240 remaining in the cavity, due to the differing refractive
indices. Identified debris 240 may then be removed by removal apparatus
120, such as a needle or forceps, for example.
Water has a refractive index of 1.333 at 25.degree. C. (see Table 1). Where
it is desired to visualize transparent debris and aqueous phase in a
bodily cavity, it is presently preferred to use a debridement fluid having
a refractive index at least 0.01, and preferably at least 0.02, more or
less than water at a given temperature and wavelength of light.
Especially where visualization of the debridement is desired, the
debridement fluid must be optically clear, although it may be desired to
use a colored debridement fluid, for example, where certain wavelengths of
light are being used or where a colored debridement fluid would otherwise
aid visualization.
In the intraocular cavity, visualization or observation in accordance with
the present invention can be conducted directly through the pupil of the
eye or indirectly using commercially available optic means, such as an
operating microscope and/or an indirect ophthalmoscope. Fiber optic
endoscopes, capable of transmitting and receiving visible light, may also
be used. Visualization of an aqueous phase and/or particulate
debris/debridement fluid interface boundaries may be aided by internal
illumination with a microscope apparatus and/or with a fiber optic scope
for removal mechanically or by suction with a fluid removal apparatus.
In still another embodiment of the present invention illustrated in FIG. 6,
debridement fluid is introduced into a closed cavity to apply diffused
counter pressure against a first tissue plane when dissecting away foreign
substances or another tissue plane overlying the first tissue plane. For
example, in the eye, foreign substances or displaced tissue can contact
the retina and form a membrane or film 35 thereon which must be removed
for proper functioning of the retina 30. Such membranes may be secondary
membranes comprising fibrovascular or fibroglial tissue growths, blood
clots, or lens capsule, nucleus or cortex, for example. Even careful
mechanical removal of the membrane can cause damage to retina in the form
of tears as the attached membrane is pulled away.
In accordance with another embodiment of the present invention,
perfluorocarbon liquid debridement fluid 200 is introduced into the eye 10
where the patient is positioned so that the retina 30 is beneath the
foreign substances or tissue plane 35 to be dissected away. As discussed
above, the relatively dense weight of the perfluorocarbon liquid presses
downward against the retina 30 as a counter force to the pulling effect of
the membrane being pulled away from the retina by dissection apparatus
130. Because the perfluorocarbon liquid is spread out across the retinal
layer, downward pressure is spread out across the retina to provide a
gentle, uniform counter force against the dissection forces.
Further according to the present invention, perfluorocarbon liquids may be
used to protect body cavity cells and tissues from foreign substances. For
example, certain ocular surgical procedures permanently replace the
vitreous with very pure silicone oil. Normally, very pure silicone oil is
not taken up by the cells of the cavity because the molecules are too
large. Over time, however, silicone molecules break down and become
absorbable by the cavity cells and tissues. Perfluorocarbon liquids also
have a large molecular size and cannot be taken up by cavity cells. Unlike
silicone, however, perfluorocarbon liquids do not break down over time.
While not wishing to be bound by any particular theory, the inventor
believes that when perfluorocarbon liquids are contacted with silicone, a
chemical reaction occurs, whereby a molecular layer of perfluorocarbon
liquid forms to envelope the silicone. Thus, in accordance with another
embodiment of the present invention, silicone molecules can be
encapsulated by perfluorocarbon liquids to protect body cells from
silicone breakdown by introducing perfluorocarbon liquid into a cavity
containing a body of silicone oil.
In still another embodiment of the present invention, the large oxygen and
carbon dioxide-carrying capacity of perfluorocarbon liquids makes them
useful for treatment of oxygen-starved cavity cells and tissues. For
example, in the eye where oxygen is essential to the health and function
of the retina, perfluorocarbon liquid introduced into the intraocular
cavity for debridement purposes may also be used to supply oxygen to
retinal cells starved of oxygen due to various retinal and/or vascular
abnormalities. In accordance with the present invention, an
oxygen-saturated perfluorocarbon liquid is injected into the intraocular
cavity, supplementing or replacing the vitreous.
Oxygen in the perfluorocarbon liquid is available to the eye cavity cells
and, similarly, carbon dioxide excreted by cells can be dissolved in the
perfluorocarbon liquid. When the oxygen content of the perfluorocarbon
liquid is spent, the oxygen can be reestablished by perfusing oxygen into
the perfluorocarbon liquid in situ on a regular basis using a cannula, for
example, to maintain a desired oxygen concentration level or by replacing
the oxygen-spent perfluorocarbon liquid with fresh oxygen-saturated
perfluorocarbon liquid until the underlying problem causing oxygen
starvation is corrected surgically or by natural healing of the eye.
Once the desired debridement procedure is complete, the debridement fluids
of the present invention may be removed from the body cavity by, for
example, active aspiration (suction) with simultaneous infusion of another
substance, such as an aqueous solution, silicone oil, or a gas, such as
air, to refill the cavity. Those skilled in the art will recognize in view
of this disclosure that other means and apparatus may be used to remove
the debridement fluids or, if desired, the debridement fluids may be left
in the cavity for extended periods of time or for future removal.
The present invention may be embodied in other specific forms without
departing from the spirit or essential attributes thereof and,
accordingly, reference should be made to the appended claims, rather than
to the foregoing specification as indicating the scope of the invention.
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